package thinkingInJava.generics.Mix;

//: generics/DynamicProxyMixin.java
import java.lang.reflect.*;
import java.util.*;
import thinkingInJava.generics.Tuple_.*;
import static thinkingInJava.generics.Tuple_.Tuple.tuple;

class MixinProxy implements InvocationHandler {
	Map<String,Object> delegatesByMethod;
	public MixinProxy(TwoTuple<Object,Class<?>>... pairs) {
		delegatesByMethod = new HashMap<String,Object>();
		for(TwoTuple<Object,Class<?>> pair : pairs) {
			for(Method method : pair.second.getMethods()) {
				String methodName = method.getName();
				// The first interface in the map
				// implements the method.
				if (!delegatesByMethod.containsKey(methodName))
					delegatesByMethod.put(methodName, pair.first);
			}
		}
	}	
	public Object invoke(Object proxy, Method method,
			Object[] args) throws Throwable {
		String methodName = method.getName();
		Object delegate = delegatesByMethod.get(methodName);
		return method.invoke(delegate, args);
	}
	@SuppressWarnings("unchecked")
	public static Object newInstance(TwoTuple... pairs) {
		Class[] interfaces = new Class[pairs.length];
		for(int i = 0; i < pairs.length; i++) {
			interfaces[i] = (Class)pairs[i].second;
		}
		ClassLoader cl =
				pairs[0].first.getClass().getClassLoader();
		return Proxy.newProxyInstance(	// interfaces 必须包含所有它后面要引用的接口
				cl, interfaces, new MixinProxy(pairs));
	}
}	

public class DynamicProxyMixin {
	public static void main(String[] args) {
		Object mixin = MixinProxy.newInstance(
				tuple(new BasicImp(), Basic.class),
				tuple(new TimeStampedImp(), TimeStamped.class),
				tuple(new SerialNumberedImp(),SerialNumbered.class));
		Basic b = (Basic)mixin;
		TimeStamped t = (TimeStamped)mixin;
		SerialNumbered s = (SerialNumbered)mixin;
		b.set("Hello");
		System.out.println(b.get());
		System.out.println(t.getStamp());
		System.out.println(s.getSerialNumber());
	}
} /* Output: (Sample)
Hello
1132519137015
1
 *///:~

